A “sex superbug” has put doctors in Australia and New Zealand on high alert amid mounting evidence that antibiotics used to treat the infection are no longer working.

The most highly resistant strain of gonorrhoea ever detected in Australia was recently found in a tourist from central Europe who contracted the STI in Sydney.

Australia’s Health Department said a new multidrug resistant type of gonococcal bacteria, dubbed A8806, was identified with similarities to an untreatable strain of gonorrhoea known as H041.

It was first discovered in Japan in 2009, when a 31-year-old sex worker who had no symptoms of the disease tested positive in a routine check-up in Kyoto and could not be treated with the commonly-used ceftriaxone.

There have also been reports of a resilient strain in Hawaii in May 2011, as well as in California and Norway.

The Australian Health Department has urged GPs to refer all cases of gonorrhoea, known as “the clap”, for culture testing and New Zealand health clinics are on a high state of alert.